Parametric mixing involves the mixing of electromagnetic waves in an optically-nonlinear medium to generate waves with new wavelengths. Parametric mixers typically comprise high power pump lasers, a signal and a nonlinear waveguide. In the process of parametric mixing, the pumps' photons are annihilated and new ones are generated at the wavelength of the signal and idler. The wavelength of the idler corresponds to its photon energy that is determined directly from the energy conservation between pumps, signal and idler photons. Gain bands are a range of wavelengths in which idler power is higher than the power of the signal at the input to the parametric mixer. Location of the gain bands depends on the phase-matching condition that is determined by momentum conservation between pumps, signal and idler photons. Prior art approaches to altering the location of the gain bands involve tuning the pumps' wavelength, which require the existence of tunable pump lasers and are therefore limited to only those spectral ranges in which such tunable laser sources exist.